High temperature pressure digestion vessel system with dual action seal

ABSTRACT

A vessel system for high-pressure reactions is disclosed. The system includes a plugged polymer cylinder reaction vessel with a pressure vent opening extending radially through the wall of the reaction vessel and a supporting frame into which the vessel is received. Complementing keying structure elements on the vessel and on the frame limit the orientation of the reaction vessel in the supporting frame and the radially extending vent opening to a defined single position.

BACKGROUND

The present invention relates to vessel systems for high pressurechemistry and in particular relates to microwave assisted chemicalanalysis such as digestion in strong acids, or extraction in organicsolvents.

The use of microwave radiation for acid digestion and solvent extractionis generally well established in the industry.

Digestion refers to several types of processes, including reducingmaterials to ash in a high temperature furnace. In the context of theinvention, however, digestion is predominantly carried out by placing amatrix (rocks, plants, soil, food, pharmaceuticals, plastics, metals) ina strong mineral acid or a combination of several strong mineral acids(sulfuric, hydrochloric, phosphoric, nitric) and heating the resultingcombination until the acids break down the matrix into elements or ions.At the end of digestion, the result is usually a clear or nearlycolorless solution that can be diluted and then tested using one or morequantitative analysis methods.

Microwave assisted closed-vessel extraction reduces solvent usagesignificantly and in particular can be used to perform a number ofextractions using amounts of solvent an order of magnitude smaller thanthat required for conventional Sierra extractions.

In the digestion context, the most significant advantage of a closedmicrowave system is the time savings it provides. Microwave digestionscan be carried out in less than about an hour as compared to 5-12 (ormore) hours for open digestions. Closed microwave systems also permitdigestion to take place at temperatures above the boiling points of theacids, while open digestions are limited to the boiling points of theacids. Microwave digestion requires proportionally less acid than opendigestions. When carried out properly, microwave digestion prevents lossof corrosive acid fumes and or a corresponding loss of volatileelements. Finally, microwave digestion eliminates the risk ofcontamination from external sources as compared to open digestion.

For certain purposes, individualized single sample testing is mosthelpful, but in many contexts, a batch system that will concurrentlydigest a plurality of similar matrices at the same time will be helpfuland efficient. Current examples include, but are not limited to, theMars 6™ instrument from CEM Corporation (Matthews N C, US; the assigneeof this application).

In the batch context, efficiency can be increased by including moresamples in each batch. Thus, currently available batch systems usuallyincorporate a turntable that will hold up to 12 digestion vesselsconcurrently. Typically, each vessel is maintained in some type ofreinforcing structure to help maintain the vessels in a closed statewhile the microwave heating step directly drives the reaction to thetemperature required to successfully carry out the digestion.

As some partial disadvantages or limitations, however, a number of suchsystems are limited to fairly small volumes, and many require connectedcontrols to measure temperature and pressure and are limited to amaximum of 12 vessels at a time. The pressure release in most closedmicrowave vessel systems is usually carried out by opening the lid ofthe vessel, even if only slightly, and allowing the gases to escape.

Additionally, some of the mechanical systems used to maintain thevessels closed under a desired pressure (and in some cases todynamically open at a certain pressure limit) require significantmechanical advantage, for example torquing to as much as 60 inch-pounds.

Based on that, a system that incorporates 12 vessels in a batch willrequire significant effort to close all of the vessels before the batchcan be carried out.

Therefore, a need exists for instruments that include a larger number ofvessels on the turntable for the batch, in which the vessels can hold atleast about hundred milliliters or more, without any connected controlsfor temperature and pressure measurement, without any metal parts, andwhile more intentionally controlling the venting of the dynamic pressureseal.

SUMMARY

In one aspect the invention is a vessel system for high-pressurereactions that includes a plugged polymer cylinder reaction vessel witha pressure vent opening extending radially through the wall of thereaction vessel, and a supporting frame into which the vessel isreceived. Complementing keying structure elements on the vessel and onthe frame limit the orientation of the reaction vessel in the supportingframe and the radially extending vent opening to a defined singleposition.

In another aspect the invention is a vessel system for high-pressurereactions that includes a polymer cylinder reaction vessel with apressure vent opening extending radially through the wall of thereaction vessel. A cylindrical reinforcing sleeve surrounds portions ofthe reaction vessel other than the radially extending vent opening. Astepped sliding closure plug is in the mouth of the reaction vessel foropening and closing the radially extending pressure vent opening withoutopening the mouth of the reaction vessel. A dimensionally stable closureis on the closure plug. The vessel is received in a supporting framewith a clamp for securing the vessel in the frame by exerting forceagainst the dimensionally stable closure. Complementing keying structureelements on the vessel and on the frame limit the orientation of thereaction vessel and the radially extending vent opening to a definedsingle position.

In another aspect the invention is a method of carrying outhigh-pressure reactions that includes the steps of heating reactants ina reaction vessel that is closed with a sliding plug, and releasinggases from the reaction vessel by sliding the plug to open a radiallyextending vent opening in the reaction vessel, but without removing thesliding plug from the vessel or otherwise opening the vessel.

The foregoing and other objects and advantages of the invention and themanner in which the same are accomplished will become clearer based onthe followed detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vessel array that incorporates thereaction pressure vessels and supporting frames of the invention.

FIG. 2 is a perspective view of a reaction vessel and a supportingframe.

FIGS. 3 and 4 are respective side elevation views taken from oppositesides of the supporting frame.

FIG. 5 is a cross-sectional view taken along lines 5-5 of FIG. 2.

FIG. 6 is a cross-sectional view taken along lines 6-6 of FIG. 5.

FIGS. 7-10 are respective plan, perspective, and cross-sectional viewsof the seat of the frame.

FIG. 11 is a cross-sectional view of the reaction vessel.

FIG. 12 is a perspective view of the reaction vessel.

FIG. 13 is a cross-sectional view of the vessel taken along lines 13-13of FIG. 12.

FIGS. 14, 15 and 16 are respective perspective, top plan, andcross-sectional views of the dimensionally stable closure.

FIGS. 17 and 18 are respective perspective and cross-sectional views ofthe stepped sliding closure plug.

FIG. 19 is an enlarged view corresponding generally to thecross-sectional view of FIG. 5.

DETAILED DESCRIPTION

The invention is the combination of a vented polymer (PTFE is exemplary)reaction vessel, a surrounding composite sleeve, a closure plug, aclosure cap on the closure plug, and a surrounding supporting frame intowhich the reaction vessel is received.

The invention provides advantages over existing vessel systems (e.g.,U.S. Pat. Nos. 8,795,608 and 6,136,276 respectively). As one improvementvessels, the invention provides a more robust vessel system that canwithstand higher temperatures and pressures, including temperatures andpressures required for difficult digestion matrices.

As another improvement, the invention offers a more secure closure witha better venting system combined with a narrower profile (i.e., morevessels in the microwave instrument at the same time).

The PTFE vessel is closed with a molded or cast PTFE plug that has threeidentifiable sections. The lowest section has a circumferential taper tomatch the circumferential taper near (but not at) the top of the PTFEreaction vessel. A middle cylindrical segment of the plug is above (inthe usual orientation) the tapered section, and a wider cylindrical topsection is above the middle segment.

The relationship between the polymer vessel and the composite sleeve issuch that the sleeve extends along the side of the vessel to at leastinclude the tapered portions of the vessel interior that meet thetapered portions of the solid plug. In previous vessels, the compositesleeve never reaches (axially) the sealing portion of the structure.

The dimensionally stable cap covers both the solid plug and the upperrim of the reaction vessel. At an excess pressure, the plug will moveaxially in the vessel creating a small gap between the tapered andmiddle sections of the plug and the vessel walls. This pressure-inducedgap creates a connection with a laterally extending pressure releaseopening in the vessel. Because the plug is stepped, however, the upperportions of the plug remain in constant contact with the upper rim ofthe reaction vessel. The structure keeps the remainder of the vesselsealed while venting takes place through the intended pressure releaseopening.

The dimensionally stable cap is in the shape of an inverted “U”, and thelegs meet the upper rim of the polymer reaction vessel to preventcircumferential expansion of the reaction vessel during gas release.

The vessel, the closure elements, and the composite sleeve are used inconjunction with a frame that includes a vertically oriented bolt thatis threaded and can be turned to exert force against the dimensionallystable cap.

Because the taper of the plug is shallow, a smaller torque can beapplied to the cap to obtain a satisfactory closure. For example, in theinvention, the frame bolt can be hand torqued to about 15 inch-pounds.By comparison, in some current vessels, the bolt must be torqued,typically in a bench holder, to about 60 inch-pounds. Avoiding a benchtorqueing step gives the invention corresponding time and efficiencyadvantages, particularly for laboratories carrying out many digestiontests on a repeated basis.

As another advantage, the vessel system and the frame are keyed orclocked so that the vessel and closure can only be inserted into theframe in a single defined position, which in turn defines the positionof the gas opening. This in turn allows a corresponding gas (vent)opening to be positioned in the frame so that exiting gases can bedirected as desired. In most cases the gas opening will be directed“inwardly;” i.e., towards the center of the usual turntable arrangementof vessels.

The closure system can be formed entirely of microwave transparent andacid resistant materials (by way of comparison, some current vesselsincorporate a metal ring for some of the circumferential sealing).Finally the overall frame is taller and narrower, than manycorresponding vessels and frames allowing for 16 vessel and framecombinations on the same turntable that holds (for example) 12 moreconventional vessels and frames.

FIG. 1 is a perspective view of a vessel array broadly designated at 30of the type used in conjunction with a turntable type microwaveinstrument such as (but not limited to) the CEM MARS6™ instrument. AsFIG. 1 illustrates, the invention provides for at least about 16 vesseland frame combinations on a turntable 25. As compared to the typical 12vessel arrangement, this represents an increase of at least about onethird, thus leading to significant efficiencies for frequent users.

The reaction vessels per se are not illustrated in FIG. 1, but thecontrol bolt 31 that carries out the clamping function is visible foreach supporting frame 32. FIG. 1 also illustrates that the turntable 25carries a plurality of T-shaped ribs 26 that engage the turntable notch42 (FIG. 2) on each frame to position and secure the frames 32 on theturntable 25.

FIG. 2 is a perspective view of the frame and of the exterior of theplugged polymer cylinder reaction vessel broadly designated at 33. FIG.2 illustrates the dimensionally stable closure illustrated as the cap34. The vessel vent opening, which is illustrated in further detail inFIGS. 5 and 19, is illustrated at 35.

The supporting frame 32 includes a frame vent tube 44 the operation ofwhich complements that of the vessel 33, and in a manner betterillustrated in FIGS. 5 and 19.

The frame 32 defines a vessel chamber 36 into which the reaction vessel33 is received. The control bolt 31 (shown with its threads 37) acts asa clamp when tightened against the dimensionally stable cap 34 toprovide a closure force that keeps the reaction vessel closed at theelevated pressures generated during the heating step.

As further details, the frame can be formed as a partially groovedworkpiece in order to save both weight and material, and provided thatthe remainder of the frame is maintained strong enough for the intendedpurpose.

FIG. 2 also illustrates that if desired, the frame 32 can be formed witha notch 42 or equivalent structure that makes it simpler or easier toalign the frame 32 on a given turntable. A frame pedestal 43 forms thebase of the frame.

FIGS. 3 and 4 are respective opposing side elevational views of thesupporting frame 32. These figures illustrate many of the same items asFIG. 2 including the clamping control bolt 31 and its threads 37, thevent frame tube 44, the turntable notch 42 and the frame pedestal 43.

FIG. 5 is a cross-sectional view taken along lines 5-5 of FIG. 2 andillustrates a number of additional items. Consistent with FIGS. 1-4,FIG. 5 illustrates the control bolt 31, the frame 32, the dimensionallystable cap 34 the frame vent tube 44, and the reaction vessel 33.

FIG. 5 also illustrates the stepped sliding closure plug 45 which restsin the mouth of the reaction vessel 33. The control bolt 31 can beturned to bear against the dimensionally stable cap 34 to any greater orlesser extent to maintain the plug in a seated position in the reactionvessel until the pressure inside the reaction vessel 33 exceeds theforce applied by the bolt 31 and the supporting frame 32. A descriptionof the structure of the stepped sliding closure plug 45 and itsoperation with respect to the other elements is given in more detailwith respect to FIGS. 17, 18 and 19.

In the illustrated embodiment, and as is common in many circumstances,the reaction vessel 33 is surrounded by a sleeve 46. The combinationoffers a number of advantages. The reaction vessel 33 is formed of apolymer that is inert to the strong mineral acids used in digestion orthe various organic solvents used in extraction. Fluoropolymers areexemplary for this purpose with polytetrafluoroethylene (e.g., Teflon®)being particularly advantageous. PTFE-type materials are flexible athigh pressures, however, and the sleeve 46 helps maintain the radialdimensional stability of the reaction vessel 33 during high temperature,high pressure reactions.

For purposes of both strength and where necessary flexibility, thesleeve is a composite structure formed of one or more layers of wovenengineering fiber and one or more appropriate polymers. The sleevedescribed in U.S. Pat. No. 6,534,140 is exemplary, but not limiting. Inthe microwave assisted context, such materials also remain transparentto microwave radiation.

To maintain axial stability while the vessel and sleeve are in the frame32, a PTFE seat 47 is positioned at the opposite end of the reactionvessel from the control bolt 31 and the closure 34, and is furtherseated in a signal transmission opening 50 which also serves to allow(for example) infrared temperature measurement of the vessel 33 during areaction.

The vessel and sleeve are sized to leave a small bottom gap 51 to allowthe reaction vessel 33 to expand slightly along its axis, and a radialgap 52 is maintained between the vessel sleeve 46 and the vessel frame32 to provide for some additional cooling.

FIG. 5 also illustrates a version of the control bolt 31 that has anoptional axial bore 53 that is used in some circumstances to providenon-invasive measurement of (e.g.) temperature or pressure.

FIG. 6 is a cross-sectional view taken generally along lines 6-6 of FIG.3. FIG. 6 illustrates the frame 32 and upper portions of the reactionvessel 33. In particular, FIG. 6 illustrates an outer ring 55 on thevessel through which the vessel vent opening 35 passes in theillustrated embodiments (e.g., FIG. 2). The outer ring 55 includes atleast one (two are illustrated) keyed portions illustrated as thenotches 56 that meet defined corners 57 in the smaller rectangularopening 60 in the frame 32. These complementing keying structuralelements on the vessel and the frame limit the orientation of thereaction vessel 33 in the frame 32 and in turn align the radiallyextending vent opening 35 to a single defined position.

The directional control of the venting also helps increase the overallsafety of the system, and helps protect an operator by limiting ventfumes to an intended defined direction.

FIG. 6 also helps illustrate the vessel chamber 61 in the frame 32 andthe larger rectangular opening 62 into which the vessel 33 can beinserted to seat in the vessel chamber. The structural grooves 40 and 41in the frame 32 are likewise illustrated.

FIGS. 7-10 illustrate the PTFE seat 47 and its seat finger 54 whichpositions the seat 47 in the signal transmission opening 50 in the frame32. In the illustrated embodiment, the seat 47 also has a physicaldesign that limits its orientation in the frame, but this is optionalrather than mandatory, and in other embodiments, the seat 47 is entirelycircular (i.e., a single diameter).

FIG. 11 is a cross-sectional view of the reaction vessel 33 takengenerally along the lines 11-11 of FIG. 12. In particular, FIG. 11 helpsillustrate that the vessel has a reaction cylinder segment 63 that makesup the majority of the axial dimension of the vessel 33. At the vesselmouth 64, the vessel defines several additional structural elements.Axially, the next element is a tapered segment 65 that in turn opens toa mouth cylinder segment 66. The outer ring 55 includes the vesselpressure vent opening 35.

FIG. 13 is a cross-sectional view of the outer ring 55 carrying the ventopening 35, and illustrating a second embodiment of the key structurefor orienting the vessel 33 in a single position in the frame 32.

FIGS. 14, 15 and 16 are respective perspective, top plan, andcross-sectional views of the dimensionally stable cap 34. These threefigures also illustrate that the closure 34 includes a seat 67 forreceiving the control bolt 31. The closure cap 34 also includes adepending annular ring 70 that engages the mouth cylinder segment 66 ofthe reaction vessel 33 and the lid section 71 of the stepped slidingclosure plug 45.

As used in this context, the term “dimensionally stable” means that thecap 34 is formed of a material that will not flex, expand, or contractunder the normally expected temperatures, pressures and resulting forcesgenerated inside the reaction vessel 33 during high-temperaturedigestion or extraction.

A current embodiment is formed of polyether imide (PEI) of which ULTEM™is a widely recognized commercial variant. In exemplary embodiments theclosure is molded or cast around glass to increase its dimensionalstability.

Related engineering polymers include polyether ether keytone (PEEK) thatlikewise has excellent mechanical and chemical resistance properties athigh temperatures. Persons skilled in this art will be able to selectone of these or other engineering polymers without undueexperimentation.

FIGS. 17 and 18 illustrate the stepped sliding closure plug 45 in moredetail. In particular, the plug 45 is formed of PTFE or equivalentmaterial with a circumferential tapered portion or segment 72 thatengages the tapered section 65 of the vessel mouth 64. A firstcylindrical segment 73 has a diameter that is slightly smaller than thediameter of the mouth cylinder segment 66 of the vessel 33. A vesselmatching section or segment 74 is on the first cylindrical section 73and has a diameter that engages the diameter of the wider mouth cylinder66 of the reaction vessel 33. A lid segment 71 is wide enough to rest onthe top edges of the vessel 33 and maintain the plug 45 at the top ofthe vessel 33.

In some embodiments, the angle of the tapered portion 72 on the plug 45differs slightly from the angle of the tapered section 65 at the mouth64 of the reaction vessel 33; e.g., by about 2°. This encourages thelowermost part of the tapered portion 72 to be the first portion toengage the mouth 64 of the reaction vessel 33. In turn, this reduces theunit force required to create a seal as compared to identical taperedangles.

The annular ring 70 on the dimensionally stable cap 34 prevents radialexpansion of the entire closure at the top of the vessel 33.

The relatively shallow taper of the mouth segment 65, designated astheta (0) in FIG. 18, is less than 45° and in some cases than 30° orless taken axially. The shallow taper, combined with the presence of thecomposite sleeve 46 that provides radial support adjacent the taperedmouth segment 65 seats the plug 45 with a more moderate force ascompared to conventional frame and vessel systems. This in turn allowsthe control bolt 31 to be tightened more easily and thus more quicklyleading to greater efficiency in multiple batch processes.

The shallow taper or bite of the vessel 33 and plug 45 provide a furtherpotential advantage in certain digestions. As the skilled personrecognizes, when the matrix contains a number of different materials(i.e., is heterogeneous), some of those materials will digest at lowertemperatures than others; indeed, some will start digesting in strongmineral acids at room temperature. Accordingly, some of these materialswill provide an early release of significant amounts of volatilematerials, frequently carbon dioxide and water vapor. In thesecircumstances, the pressure inside the vessel 33 can reach the matchingpressure of the bolt 31 and frame 32 against the plug 45 at a relativelylow temperature and before the remainder of the matrix digests. At thatpoint, the plug 45 will move slightly in an axial direction to permit anearly pressure release, but will return quickly to its seated positionso that the reaction in the vessel 33 continues to the highertemperatures required to obtain a full digestion of the more difficultportions of such matrices.

FIG. 19 is an enlarged cross-sectional view corresponding to the topportions of FIG. 5. In particular, FIG. 19 shows the dynamic nature ofthe pressure release of the invention and is essentially a snapshot ofthe vessel system in a pressure-release orientation.

FIG. 19 represents the state in which the pressure in the reactionvessel 33 has urged the plug 45 upwardly against the dimensionallystable cap 34. This disengages the vessel matching section from itsseated position adjacent the vessel vent opening and moves it axially sothat the first cylindrical section 33—which has a diameter slightlysmaller than the interface of the mouth cylinder segment 66 of thevessel 33—is adjacent the vessel vent opening 35 and the circumferentialtapered portion of the plug 45 is slightly unseated from the taperedmouth segment 65 of the vessel 33.

This slight disengagement is sufficient to allow gases to escape fromthe interior of the reaction vessel 33 past the circumferential taperedportion and first cylindrical section 73 of the plug 45 and then throughthe vessel vent opening 35. As illustrated and exemplary, the frame venttube 44 is oriented and aligned with the vessel vent opening 35 so thatthe vented gases travel immediately through the frame vent tube; i.e. atan intended position and in an intended direction. This alignment is, ofcourse, a result of the key elements described with respect to FIG. 6.

During the escape of gases, however, the vessel matching section 74remains entirely engaged to upper portions of the mouth cylinder segment66 of the vessel 33 so that the vessel remains otherwise closed at itsmouth. When sufficient gas has been released to reduce the pressureinside the vessel to equilibrate with the force applied by the controlbolt 31, the bolt 31 and the dimensionally stable cap 34 urges andslides the plug 45 back into a fully seated position that prevents gasesfrom escaping.

FIG. 19 also illustrates that the outer ring 55 serves the secondpurpose of axially positioning the composite sleeve 46 in relation tothe reaction vessel 33.

In a method context, the invention includes the steps of heatingreactants in a reaction vessel that is closed with a sliding plug, andthen releasing gases from the reaction vessel by sliding the plug toopen a radially extending vent opening in the reaction vessel, butwithout removing the sliding plug from the vessel or otherwise openingthe vessel.

In exemplary embodiments, the method includes heating reactions insidethe vessel using microwave radiation in a microwave transparent polymervessel, and exerting a defined force against the sliding plug topreclude the plug from sliding until the gas pressure in the vesselexceeds the defined force being applied.

In the drawings and specification there has been set forth a preferredembodiment of the invention, and although specific terms have beenemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, the scope of the invention being defined inthe claims.

1. A vessel system for high-pressure reactions comprising: a pluggedpolymer cylinder reaction vessel with a pressure vent opening extendingradially through the wall of said reaction vessel; a supporting frameinto which said vessel is received; complementing keying structureelements on said vessel and on said frame to limit the orientation ofsaid reaction vessel in said supporting frame and said radiallyextending vent opening to a defined single position.
 2. A vessel systemaccording to claim 1 wherein said supporting frame has a vent tube thatis aligned with said radially extending opening in said reaction vesselwhen said reaction vessel is keyed into said supporting frame.
 3. Avessel system according to claim 1 wherein said supporting frame furthercomprises a clamp that bears against said plugged vessel to keep saidvessel closed at defined pressures generated by reactions inside saidvessel.
 4. A vessel system according to claim 2 wherein said keyingstructure elements include: defined corners in said supporting frame;and a keyed portion of said reaction vessel for engaging said definedcorners in said supporting frame.
 5. A vessel system according to claim3 further comprising: a dimensionally stable cap on said plugged vessel;and a threaded bolt in said frame that bears against said dimensionallystable cap and said plugged reaction vessel.
 6. A vessel systemaccording to claim 1 wherein said polymer reaction vessel is formed ofPTFE.
 7. A vessel system according to claim 6 further comprising acomposite sleeve around said reaction vessel and formed of a pluralityof layers of woven fabric and polymer.
 8. A vessel system forhigh-pressure reactions comprising: a polymer cylinder reaction vesselwith a pressure vent opening extending radially through the wall of saidreaction vessel; a cylindrical reinforcing sleeve surrounding portionsof said reaction vessel other than said radially extending vent opening;a stepped sliding closure plug in the mouth of said reaction vessel foropening and closing said radially extending pressure vent openingwithout opening the mouth of said reaction vessel; a dimensionallystable closure on said closure plug; a supporting frame into which saidvessel is received; a clamp for securing said vessel in said frame byexerting force against said dimensionally stable closure; andcomplementing keying structure elements on said vessel and on said frameto limit the orientation of said reaction vessel and said radiallyextending vent opening to a defined single position.
 9. A vessel systemaccording to claim 8 wherein the inner face of said reaction vesselcomprises: a reaction cylinder segment; a mouth cylinder segment widerthen said reaction cylinder segment; and a tapered segment that extendsbetween said reaction cylinder segment and said mouth cylinder segment.10. A vessel system according to claim 9 wherein said radially extendingvent opening extends through said wider mouth cylinder segment.
 11. Avessel system according to claim 10 wherein said stepped plug comprises:a tapered portion that matches the tapered section of said reactionvessel; a first cylindrical section adjacent said tapered portion thathas a diameter slightly smaller than the diameter of said wider mouthcylinder; a vessel matching section on said first cylindrical sectionwith a diameter that matches the diameter of said wider mouth cylinder;and a lid section on said vessel matching section; so that excesspressure in said reaction vessel urges said plug to move in said mouthportion to allow gas to move past said tapered portion of said plug,past said first cylindrical section, and out of said vessel ventopening, while the vessel matching section of said plug maintains thewider mouth cylinder of said vessel closed.
 12. A vessel systemaccording to claim 11 wherein said frame defines a chamber for receivingsaid reaction vessel and in which one face of said frame defines arectangular opening into which said reaction vessel and reinforcingsleeve can be inserted; and the opposite face of said frame defines asmaller rectangular opening that is smaller than the diameter of saidreaction vessel and sleeve to thereby help seat said reaction vessel andsaid sleeve in said frame.
 13. A vessel system according to claim 12wherein said complementary keying structure elements comprise: an outerring on the outside of said reaction vessel at a position correspondingto said inner face mouth cylinder segment; and a pair of keying notchesin said outer ring that engage opposing sides of said smallerrectangular opening in said frame.
 14. A vessel system according toclaim 13 wherein said frame includes a vent tube that is aligned withsaid radially extending pressure vent opening in said reaction vessel sothat gases released through said radially extending vent opening in saidreaction vessel are directed through said vent tube in said frame.
 15. Avessel system according to claim 9 wherein said reinforcing sleevesurrounds at least said tapered segment of said interface of saidreaction vessel.
 16. A vessel system according to claim 11 wherein saiddimensionally stable closure includes a depending annular ring thatsurrounds both said lid section of said sliding closure plug and upperportions of said mouth cylinder segment of said reaction vessel.
 17. Amethod of carrying out high-pressure reactions comprising: heatingreactants in a reaction vessel that is closed with a sliding plug; andreleasing gases from the reaction vessel by sliding the plug to open aradially extending vent opening in the reaction vessel, but withoutremoving the sliding plug from the vessel or otherwise opening thevessel.
 18. A method according to claim 17 further comprising heatingthe reactions using microwave radiation in a microwave transparentpolymer vessel.
 19. A method according to claim 18 further comprisingexerting a defined force against the sliding plug to preclude the plugfrom sliding until the gas pressure in the vessel exceeds the definedforce being applied.